OSP Fiber Optic CableInstallation and Handling Guidelines for Underground and Aerial Applications
Howard KempMember of Technical StaffOFS Customer Support Engineering
OutlineCable & Fiber DescriptionGeneral PrecautionsUnderground Placing Equipment & MaterialsPulling TensionMinimum Bend RadiusInstallation TechniquesCable CoilingAerial Span LimitationsAerial Placing EquipmentPlacing MethodsSlack Storage
Fortex™ DTSingle Jacket Loose Tube Cable
Dielectric cableCompletely dry cable designRecommended for duct or lashedaerial applications
Meets or exceeds Telecordia GR-20,RUS PE-90, and IEC 794-1
Up to 288 fibers – 12 fibers/tube(2.5 mm tube)
Up to 432 Fibers – 24 fibers/tube(3.5 mm tube)
Fortex™ DTLight Armored Loose Tube Cable
Corrugated steel armor tape & PE jacketCompletely dry cable designRecommended for duct, direct buried or lashedaerial applications
Meets or exceeds Telecordia GR-20,RUS PE-90, and IEC 794-1
Up to 288 fibers – 12 fibers/tube(2.5 mm tube)
Up to 432 Fibers – 24 fibers/tube(3.5 mm tube)
AllWave® Fiber
wavelength (nm)E
0
0.3
0.6
0.9
1.2
1300 1400 1500 1600
Wavelength (nm)
Atte
nuat
ion
(dB
/km
)
O LCS
Zero water peak single mode fiber
no hydroxyl ions in fiber, so there’s no E-band “water peak”
Cable Installation- General Precautions
Observe maximum rated cable tensionObserve minimum bend diametersAvoid excessive cable twistStorage Temperature
-40°F to 167°F (-40°C to 75°C)Installation Temperature
-22°F to 140°F (-30°C to 60°C)
InnerductUnderground installation (innerduct in conduit)
Diameter Ratio ≤ 0.67Larger diameter innerduct may be required for cable blowing
Direct buried installationRecommend smooth-wall or ribbed innerduct (not corrugated)Distribution networks: minimum ID = 1.25 inchesLong haul networks: minimum ID = 1.5 inches
Cable O.D.Cable O.D.
Innerduct I.D.Innerduct I.D.
= Diameter Ratio= Diameter RatioCable ODCable OD
Innerduct IDInnerduct ID
Cable LubricantsRecommended
Polywater (American Polywater Corp.)Hydralube Blue (Arnco)or equivalent
QuantityBased on cable installation lengthFollow manufacturer’s recommendations
Do not use detergents (soaps)May cause stress cracking of cable jacket
Cable Installation Equipment- Capstan Winch
Hydraulic motor used to drive a capstan
Typical pulling speeds ~ 75 – 150 fpmTypical pulling distances ~
1000 – 2500 ft
Capstan Winch- Precautions
Pressure gauge displays hydraulic pressure – not cable tensionGauge must be calibrated to indicate cable tensionHydraulic relief valve needs routine calibration to
confirm and/or adjust bypass valve at 600 lb tension
Maximum Pulling Tension
Maximum Rated Cable Load = 600 lb (typical)Maximum installation force must not exceed 600 lbMaximum installation force must be controlled using
Calibrated capstan winchesBreakaway swivelsSlack cable loops
Controlling Installation Tension- Breakaway Pulling Swivel
Attached between pulling tape and cable gripSeparates at 600 lb load
Internal pin breaks at rated loadConfirm proper load rating of internal pin
Should not be pulled over sheaves and/or capstans (may weaken pin)
Controlling Installation Tension- Capstan Winch
Maintain slack loop on pull-off side of intermediate capstans
– Prevents additive pulling force of multiple capstans
– Provides a buffer for adjusting pulling speeds
Slack loopSlack loop
Minimum Bend RadiusFortex™ DT cables (loose fiber designs)
Under load (during installation)– Rmin = 15 × OD
No load (after installation)– Rmin = 10 × OD
Note: diameter = 2 × radius, therefore– Dmin = 30 × OD (during installation)– Dmin = 20 × OD (for storage coils)
Controlling Bend Diameter
Bend diameter is controlled by
Using correct diameter capstansUsing correct diameter cable sheavesForming cable storage loops in correct diameter
Cable Storage in Handhole
W
Minimum inside dimension of hole mustbe large enough to allow slack coils to bestored without violating the minimumrecommended slack coil diameter.
Minimum bend diameterfor slack storage:D >= 20 x Cable OD
Splice Case
D
Cable Installation Equipment- Blowing / Jetting Machines
Use compressed air to blow cable and drive wheels/belt to push cableTypical installation
speeds ~ 150 - 200 fpmTypical installation
distances ~ 3,000 ftRequires airtight
innerduct couplings
Blowing / Jetting Machines- Precautions
Conduct cable slip test per equipment manufacturer’s instructionsConduct cable buckling test per equipment
manufacturer’s instructionsObserve maximum operating pressuresUse proper innerduct inserts & sealsUse proper cable inserts & sealsConfirm integrity of innerduct and couplersClean and lubricate innerduct
Cable Installation Techniques
Single PullBackfeed TechniqueForward Feed TechniqueIntermediate Assist
Single Pull
Install entire cable from splice location to splice location in one continuous operation
MH 3 MH 4
Figure-8 MethodUsed to increase distance between splice pointsUsed when cable length exceeds equipment availability
BackfeedsForward feeds
Figure-8 Method- Precautions
When figure 8-ing large heavy cables, use the“Smear Method” for stacking the cable layers
Offset the cross-over points in each layer by about 4 inchesThis will help prevent sheath dents caused by the cable’s own weight
Limit the height of the figure-8 stack to 2 ft
Figure-8 Method
Standard Figure-8 “Smeared” Figure-8
“Figure-8 Eliminator” MachinesFigure-8 Eliminator machines are used
to automate the figure-8 processEquipment may cause fiber and/or
cable damage and is NOT recommended for use with OFS cable Cable subjected to a Cable subjected to a
combination of tension, combination of tension, bending, and twistingbending, and twisting
Backfeed Placement
Position cable reel near mid-point of cable routeInstall first half of the cable using standard techniques
MH 3 MH 5MH 4
Backfeed Method (cont.)
Remove remaining cable from reel and figure-8
MH 5MH 4
Cable Backfeed (cont.)
Access inside end and feed in opposite directionInstall remaining cable from figure-8 stack to splice location
MH 4MH 3 MH 5
Forward Feed MethodPull slack cable to intermediate manholeFigure-8 slack cable on ground
MH 4MH 3
Forward Feed Method (cont.)Flip figure-8 stack to access cable endPull cable to splice locationCan use multiple forward feeds if required
MH 3 MH 5MH 4
Intermediate AssistUse two or more winches to distribute the
installation force
Intermediate Assist
Cable CoilingUse proper coiling methods to prevent excessive cable twist and cable damageObserve minimum storage coil
diameterRecommended coiling methods
Fold-over methodTeardrop methodGarden Hose method
Summary
Maximum Pulling Tension = 600 lbMinimum Bend Radius (Fortex™ DT cable)
During Installation: 15 × OD After Installation: 10 × OD
Use of cable jetting/blowing equipment is recommendedMaintain slack loops at capstan winchUse of “Figure-8 Eliminator” machines is not
recommended and Will Void Cable WarrantyEliminate cable twist with proper coiling methods
Aerial Plant Design
Aerial cable plant must be designed to meet NESC storm-load requirements
Ensure public safetyPrevent aerial plant from falling downRequires a strength design (does not consider fiber stress)
Fiber-optic cable plant must also be designed to limit the maximum fiber stress
Ensure long-term reliability of the optical fibersSelect support strand and span length to limit the fiber stress to acceptable levelsRequires a stiffness design (usually the limiting design)
NESC Storm-Load Districts
NESC Storm Load Conditions
NESC Ice, Wind, and Temperature Load Conditions
STORM-LOAD DISTRICTENVIRONMENTAL CONDITION HEAVY MEDIUM LIGHT
Radial Thickness of Ice 0.5 inch 0.25 inch 0
Horizontal Wind Pressure 4 lb/sq-ft 4 lb/sq-ft 9 lb/sq-ft
Temperature 0 ºF +15 ºF +30 ºF
Constant to be added 0.3 lb/ft 0.2 lb/ft 0.05 lb/ft
Fiber Stress Storm-Load Conditions
Ice, Wind and Temperature Conditions Usedfor the Stiffness Design of Aerial Fiber-Optic Cable
STORM-LOAD DISTRICTENVIRONMENTAL
CONDITIONHEAVY MEDIUM LIGHT ALL
Radial Thickness of Ice 0.5 inch 0.25 inch 0 0
Horizontal Wind Pressure 4 lb/sq-ft 4 lb/sq-ft 9 lb/sq-ft 0
Temperature +32 ºF +32 ºF +100 ºF +170 ºF
Maximum Recommended Span Lengths
STORM LOAD DISTRICTSUPPORT
MESSENGERHEAVY MEDIUM LIGHT
Fortex® DT Loose Tube Cables
1/4 inch EHS 400 ft 800 ft 900 ft
Pre-Construction PlanningDetermine Splice Locations
Insure that the splice location is accessiblePlan splice locations at corner poles to simplify cable installation
Determine Cable LengthsInclude slack cable for splicingDetermine the length and quantity of maintenance coils
Determine the Installation MethodStationary Reel MethodMoving Reel Method
Aerial Cable Placing- Tools & Materials
Aerial Line Truck or Bucket Truck
Cable Trailer or Reel Carrier
Cable Winch
Aerial Cable Placing- Tools & Materials
Cable Stringing Blocks
Cable Guide
Radios
Aerial Cable Placing- Tools & Materials
Pull Rope
Pulling Grip
Pulling Swivel
Snow Shoes
Aerial Cable Placing- Tools & Materials
Cable Lasher Lashing wireLashing Wire Clamps
Stationary Reel Method
WINCH
CABLE BLOCKSROPE
PULLING GRIP &BREAKAWAY SWIVEL QUADRANT
BLOCK STRAND
COMMUNICATION COMMUNICATION
Stationary Reel Method
1. Install cable blocks on pole line2. Install pull rope through cable blocks3. Pull cable through cable blocks
Observe maximum cable tensionObserve minimum bend radius of cable
4. Lash cable to support messenger
Stationary Reel Method- Precautions
Use sufficient number of stringing blocks to support the weight of the cableUse a cable guide to support the cable at the messenger Use adequately sized cable blocks at corner polesUse non-metallic pull ropeUse tension-limiting pull winch (or break-away swivel)Pull cable at a safe, steady speed to avoid surgingMaintain constant radio communications
Aerial Installation Methods- Moving Reel Method
Cable reel driven along pole line, cable lifted up to strand and lashed in a one-step installationDoes not require cable blocks or pull linesMost efficient placing method
Moving Reel Method- Precautions
Must have unobstructed access to support messengerPosition reel carrier 30 to 50 ft in front of cable lasherKeep reel carrier closely aligned with support messengerDo not feed cable through roller fairlead (aerial line truck only)Monitor reel rotation and prevent surgeDo not use brake on cable reel
Slack Storage- Snow Shoes
Slack Storage- Storage Coils
Questions?
For further information, please contactHoward [email protected]
Or visit our website atwww.ofsoptics.com
Or call OFS Customer Care1-888-FIBER-HELP (888-342-3743)(1-770-798-5555 from outside the USA)